Camera-focusing device.



JULIAN A. DIMOCK, OF DENNING, NEW YORK.

CAMERA-FOCUSING DEVICE.

Specification of Letters Patent.

Patented Sept. 3, 1907.

Application filed August l, 1906. Serial No. 328,657.

To all whom it may concern:

Be it known that I, JULIAN A. DIMOCK, a citizen of the United States,residing at Denning, in the county of Ulster and State of New York, haveinvented certain new and useful Improvements in Camera-Focusing Devices,of which the following specification and accompanying drawing illustratethe invention in a form which I now regard as the best out of thevarious forms in which it may be embodied.

The object of this invention is to provide a device for focusing handcameras in instantaneous photography and it consists in an improved formof focusing scale so constructed that the proper or approximate focuscan be attained by means of the sense of touch, so that on the one handthe operators vision isv left practically unoccupied and free to followthe course of a moving object, and on the other hand the distance awayof the object from the camera may be ascertained by the sense of touchwhile the operator-s eyes are on the groundglass.

Of the accompanying drawings, Figure l represents a side elevation of areflecting camera provided with my improved focusing device; Fig. 2represents a section on the line 2-2 of Fig. l, Fig. 3 is an enlargedview showing the manner of using the invention.

The same reference characters represent the same parts in all thefigures.

I have shown the device in connection with a reflecting camera, since itis this type of instrument which is best adapted to quickly photographmoving objects and which affords certain particular results inconnection with my invention.

l0 is the box of the camera Il is the lens mounted upon a slidingsupport l2, for the purpose of focusing, and I3 is the extensiblefocusing hood, through which the image may be observed on a ground-glass23 in the top of the box, as reflected from a mirror 14 within the box.In this type of instrument there is often employed a focal-planeshutter, which I have indicated at 24, consisting of a sltted curtainmoving in front of the dry-plate, under the impulse of a spring, whichis wound up for each exposure and released by a thumbpiece or catch,such as l5 in Fig. 2, located on one side near the front of the box. 16indicates the winding knob. The actuation of catch l5 first releases andthrows the mirror 14 out of the path of the light rays, permitting theexposure to be properly made upon the dryplate, and their releases theshutter 24. These arrangements are familiar in the art and are hereshown only in a general way.

I7 is the usual focusing knob attached to the outer end of a rod 18carrying pinions vI9 which mesh with the teeth of racks 2O attached tothe lens-slide l2. I add to this knob a radial pin or projection 2l,constituting an index adapted to travel over a segmental scale, whichmay be composed of headed pins 22 driven into the camera-box.Preferably, the positions of these pins correspond to the importantfocal distances. They are arranged with relation to the pin or pointer2l, so that the same linger or lingers of the operators hand employed toadjust the pin 2l and thus turn the shaft I8 and focus the camera, canat the same time. by the sense of touch, feel the scale-points 22 andadjust the pin 2l in desired relation to any one of these points. Thesepoints I term prominences, using the term in a generic sense to indicateeither a positive or negative projection, the only necessaryconsideration being that they shall be readily identifiable by the senseof touch. exercised in the manner set forth. A little experience withthis scale enables the operator to instantly adjust the lens to an exactfocal distance and all that he is required to do further, in order toobtain a correctly focused image without looking on the ground-glass, isto properly estimate or otherwise determine the distance of the objectaway from the camera at the moment of exposure. It will be noted thatthe focusing device is located on one side of the camerabox, near itslower forward corner, which enables the Operator, with the hand on thatside, to support the camera-box and at the same time focus the lens. Theslnitter-releasing knob l5 is located in a corresponding position uponthe opposite side. These cameras when of considerable size are usuallyoperated by holding the rear end of the box against the body or on theknees, while the hands support the front end and at the same time directthe camera toward the object, focus it and release the shutter.

lil/fiile my invention may be so constructed that the pin 2l, or anequivalent, touches the scale, it is i11- dispensabl'e to have the scalepoints so impressed or marked to make them readily perceptible by thesense of touch and also that the projection 2l, or its equivalent, shallbe normally free to move over the scale by the mere exertion of pressurein the direction of its focusing movement.

It will be noted that my invention works in coperation with theground-glass for the securing of certain results peculiar to its use onreflecting cameras. that is, cameras which enable the image to befocused by the main lens on a ground-glass and an exposure madeinstantly thereafter without the intervention of one or more separateoperations. Thus since the scale-points 22 correspond to focaldistances, it is possible to know the distance of the object from thecamera at the instant of exposure, by knowing that the object wascorrectly focused on the ground-glass and observing the focal distanceby the sense of touch without having to look at the scale. The distanceof any comparativelynear object can thus be obtained with the operatorseyes on the ground-glass and his fingers on the focusing scale, andmoreover the operator can place himself at a` desired distance from theobject by setting the scale and moving the camera into the correspondingfocal distance as shown by the ground-glass. This eliminates theexercise of judgment in some situations where its elimination works abenefit.

The mechanical embodiment of my invention may be considerably variedwithin the scope of the claims in the way of the shape and location ofthe scale, the shape of the path of movement of the index, establishmentof one or the other member as the movable part, and such matters. It isessential however that the scale shall have definite boundaries7 thatis, a beginning' and an ending with reference to some Vfixed point orbase so that the different scale points may have [ixed and in variablevalues or correspondence with definite focal distances. Such a scale Iterm a. delimited one, but the delimitation may be effected in variousways either in fixed or movable scales. ln the illustration here givenit is effected by making,` the scale-points stationary on thecamera-body and causing the index 2l to have not more than one completerevolution.

What I claim as new and desire to secure by Letters v Patent is:

1.1Vn a focusing; device, the combination, with the camera-box, of two1nembers,-0ne of which is connected with the focusingl mechanism of thecamera and normally free to move over the other by pressure exerted inthe direction of its focusinl movement, one of said members being anindex and the other a delimited scale composed ot' prominencescorresponding`- to the focal distances, said prominences beinbl`distinguishable by the sense f touch exerted by the iingers of theoperator-'s hand performing a relative adjustment of the two members.

2. A camera-focusingl device comprising, in combination with the camera,a stationaryv scale,composed of raised points corresponding in positionto the focal distances, and a revolvingl index connected with thecamerrefocusing mechanism and so located as to sweep over said scale ata substantial distance away from the scale-points, but in sutlieientlyclose proximity thereto to enable the points to be felt by the lingerswhich move the index.

The combination with a reflecting camera having provision for focusingon a ground-glass by means ofthe main lens while the sensitive surfaceis in condition for exposure by the release of the shutter, of afocusingl` device including a delimited scale and an index, one oi'which is movable over the other and connected with thecamera-focusingmechanism, said scale having prominences distinguishableby the sense of touch, whereby the focal distance oi' the object may bedetermined while the operator-'s eyes are on the ground-glass.

In testimony whereof I have hereunto set my hand in the presence of twosubscribing witnesses, the th day of July 100G.

JULIAN A. DIMOCK.

Witnesses iL W. SrMCr/r, G. A. WonLnrA

